This invention relates to an axial adjustment device for tapered intermediate rolls in a multi-roll, or cluster mill stand.
More particularly, the invention is concerned with an axial adjustment device which comprises at least one adjusting device or mechanism operable in the axial direction of the intermediate rolls and working through an individually associated shift bar on the neck of the associated intermediate roll which is provided with a pivot bearing.
A device of this kind is prior art and described in GE-PS 955 131.
In known multi-roll or cluster mills, e.g. in a 20 roll stand, an axial shift or adjustment is applied to the intermediate rolls in order to relieve the load of the working rolls in the marginal regions of the rolled strip. In the working zone, i.e. in the zone where the rolls engage with the workpiece, the working rolls are flattened out by the rolling force, while their free ends which are not in contact with the workpiece are not subject to this load and retain their original circular cross-sectional form. Consequently, the applied rolling force increases in the region of the edges of the workpiece, leading to a higher `draft`, i.e. the edges of the workpiece are over-rolled and suffer a stronger reduction.
As a result of the provision of intermediate rolls with tapered ends, and because the intermediate rolls are axially adjustable, the working rolls can yield, or flex under increasing rolling forces in the marginal regions of the workpiece and thus avoid excess pressure loads and an over-reduction of the edge zones in the rolled strip.
In conventional mills, which have been in use for many decades, the axially effective adjusting axis or spindle is secured to one neck of the associated intermediate roll by means of a shift bar and with the interposition of a pivot bearing. In order to change the intermediate roll, which is frequently necessary, the connection between the roll neck and adjusting device must be manually operated, and, it is necessary for an operator to go to the drive side of the roll stand to perform this operation. Each of the intermediate rolls is provided with its own individually associated shift bars.
Another disadvantage with these conventional arrangements, resides in that special precautions must be taken to prevent slipping or dropping of the two upper intermediate rolls.